Circuit-controlling contact.



E. M. HEWLETT. CIRCUIT CONTROLLING CONTACT.

APPLICATION FILED OUT. 29, 1910.

Patented Sept. 30, 1913.

Witnesses:

W M (Y ///s Attbrney.

EDWARD u. HEWLETT, or scHnNncTAnY, NEW YonK, AssIsNoR TO GENERAL TRIO cournmr, A conroRArIcN or NEW YORK.

ELEC- CIBCUIT-CONIROLLING CONTACT.

Specification of Letters Patent. I Patented Sept. 30, 1913.

Application filed October 29, 1910. Serial No. 589,689.

To all whom it may concern;

Be it known that I, Eowm M. Human, a citizen of the United States, residing at Schenectady, county of New York, have invented certain new and shunt contacts of a circuit breaker, should.

make good electrical engagement with each other when the circuit controlling device is in the closed position, and that the contacts separate in a definite manner so that the are formed when the circuit is finally broken will occur at some definite and predetermined point on the contacts where the damage done by the arc will be a minimum.

The object of my invention is to provide coiiperating contacts, particularly adapted for use as shunt contacts in a circuit breaker, but also useful in other devices, in'which there is a simple and rugged mounting of such a character that as the contacts are brought together they make good electrical contact, in which the movement of the contacts relatively to each other is positively controlled in such a manner that as the circuit is opened the contacts separate in a definite and predetermined manner, the shunt contacts for circuit breakers being preferably arranged to swing away from each other at the bottom to such an extent that the final break in' the circuit takes place near the upper edge of the contact in which the contacts are yieldingly held in proper relation by a single spring or similar device mounted so as to be fully protected by the contacts from accident or injury; and which may be applied to any of the well-known and standard forms of circuit breakers and circuit controlling devices without requiring extensive alterations and changes in them. When my in ention is embodied in shunt contacts of which the engaging surfaces are partly metal and partly carbon the contacts of Schenectady; State r have such a movement relatively to each other that as the circuit breaker opens the metallic surfaces of the shunt contacts swing away from each other while the carbon surfaces are'still in firm engagement, so. that arcing takes place on the carbon surfaces.

My invention will best be understood in (connection with the accompanying drawings in which, merely for the purpose of illustrating one of the various forms in which my invention may be embodied, I have shown the form which I, at the present time, consider to be the best embodiment of my invention when applied to shunt contacts for circuit breakers and in which Figure 1 is a view of a portion of a circuit breaker having shunt contacts embodying my invention, part of oneof theshunt contacts being shown in section; and Fig. 2 is a view of thesame circuit breaker in the partly open position in which the main brush is out of engagement with the main contact while the shunt contacts are on the point of separating.

In the particular form of device shown in the drawings, a circuit breaker of. any wellknown type is mounted upon a suitable panel or support, the circuit breaker being so mounted that the main brush and the shunt contacts swing in a vertical plane and the shunt contacts are above the main contacts. shown, the main stationary'contact 1 is secured to thepanel or switchboard and cooperates with the brush 2, while immediately above the main contacts are the secondary metallic contacts Sand 4 which separate a moment after the main contacts when the circuit breaker opens. The drawings also show the upper end ofa pivoted or swinging arm 5 carrying a shunt contact 6 which cooperates with another shunt contact 7 mounted upon the base or panel; By-any suitable operating mechanism the arm 5 is actuated and swung about its pivot in such relation to themain brush 2 of the circuit breaker that the circuit remains closed through the shunt contacts after the main contacts have separated so that the arcing due to the final rupture of the circuit takes place between the shunt contracts 6 and 7 In the particular form of contact indicated In the particular circuit breaker 3 in the drawings, each shunt contact 6 and 7 consists of a lower part of metal and an upper part or block of carbon which is held in rigid relation to the metallic part of the shunt contacts in any suitable or well known way, but if desired the metal part may be omitted so that the whole engaging face of the contact is carbon.

In order that the shunt contacts 6 and 7 may be in good electrical engagement when the circuit breaker is clbsed they should be held in resilient engagement with each other. It is also very desirable that the shunt contacts be arranged to cause the final break to take place between the carbon surfaces of the shunt contacts so that the unavoidable arcing will cause a minimum amount of damage. tion, the shunt contact 7 is mounted to cause the metallic portions of the shunt contacts to swing away from each other while the carbon portions are still in firm engage- ,ment so that the current flowing through the shunt contact is transferred from the metallic portions of the contacts to the carbon portions, and the final break, as well as any arcing caused thereby, takes place between the carbon portions of the shunt contacts. This result is obtained by causing the shunt contact 7 toswing lengthwise of the contact 6 in such a path that points at difierent ends of the contact 7 traverse different paths which are so related that the lower ends of the contacts are swung away from each other, while the upper ends of the contacts are still in firm engagement. In the particular arrangement shown in the drawing for securing the desired relative movement of the shunt contacts, the contact 7 is carried upon a metallic support 8 mounted at one end upon a pivot 9 secured to the outer ends of two links 10. Since Fig. 1 is a sectional view only, one of the links 10 appears in Fig. 1 while the other is seen in Fig. 2. The links 10 are in turn pivoted at the other ends upon a pivot 11 rigidly mounted in a casing or support 12 secured to the switchboard or panel above the main contacts of the circuit breaker. The upper end of the'support 8 and of the contact 7 therefore swing about the pivot 11 as a center and describe a circle having a radius equal to the length of the links 10. The

. lower end of the contact and of the support '14:. Through the slots 14 extends a pin 15 In accordance with my invensecured to the outer ends of two links 16 considerably shorter than the links 10 and mounted upon a fixed pivot 17 in the frame work 12. The short links 16 are preferably mounted to bring their outer ends between the two lugs 13. As a result of the construction'above described, movement of the contact 7 relatively to the base or panel causes the two ends of the contact to de scribe arcs of circles having difierent radii, and this movement is further modified by the lost motion which takes place between the lower end of the contact and the links 16 on account of the pin 15 and the slots 14. Since the shunt cont-acts of a circuit breaker are usually mounted to swing in a vertical plane, the weight of the contact 7 will tend to carry it into the position shown in Efigz but in order to make sure that. there will be the proper relative movement between the two contacts, I prefer to provide means for resiliently holding the contacts in en gagement when the circuit breaker is closed, and in accordance with my invention this result is accomplished with a single spring which may be made strong and rugged and is preferably so mounted that it is covered by the contacts 7 and is protected from accidental injury. In the particular arrangement which I prefer, the support 8 is provided with a lug or projection 18 extending beyond the pivot 9 and connected at its projecting end to one end of a spring 19 which has its other end connected to a pin 20 rigidly mounted in the casing 12. When 1 0 the circuit breaker is closed the contacts are in engagement and the parts are in the position shown in Fig. 1 with the spring 19 under tension, while as the circuit breaker opens the spring 19 contractsand forces the contact 7 down into the position shown in Fig. 2, with the result that the contact 7 slides longitudinally over the surface of the contact 6 and. at the same time its lower end swings away from the lower end of the contact 6 into the position shown in Fig. 2, so that the final rupture of the circuit must take place between the carbon surfaces of the shunt contacts.

In order to insure proper relative movement of the contacts and to bring all parts of the surfaces of the contacts 6 and 7 into firm engagement the slots 14 in the lugs 13 are madelong enough to permit the lower end ofthe contact 7 to swing toward and away from the base and to allow considerable lost motion between the lower end of the contact 7 and the links 16. As a result of this lost motion the contacts are in goodelectrical engagement with each other during the greater portion of the time that they are in contact and separate in the proper way to throw the arc to the upper edges of the carbons.

The shunt contact 7 may be electrically 13o connected to the circuit in many ways which will be apparent to those skilled in the art, but I prefer to connectit in the manner shown in the drawings by means of a flexible connection 21 fastened at one end to the lower end of the support 8 and to the contact 7 and at the other end to a projection or lug 22 which is connected mechanically and electrically to the main contact 1 so that the circuit. is completed from the main contact through the flexible connection 21 'to the shunt contact 7. The lug or projection 22 also acts as a stop to limit the downward movement of the contact 7, as shown in Fig. 2.

In a circuit controller having contacts embodying my invention, the contacts are resiliently held in engagement with each other and are compelled to move relatively to each other in such a Way thatitheir separation takes, place in a predetermined way and at predetermined points. Where the invention is embodied in shunt contacts having 'both metallic and carbon parts the opening of the circuit breaker separates the contacts in such a way that the metallic portions of the contacts first separate and cause the current to be transferred to the carbon portions where the final break takes place with a minimum of damage. A simple and rugged mounting compels the contacts to move 1n the desired way, while the resilient engagement of the contacts is effected by connecting said' contact to two pivots fixed I out of alinement and in the plane of movement of said contact to cause said contact to swing bodily about said pivots, and a cooperating movable contact mounted to move into and out of engagement with said first named contact and thereby swing said. first named contact about its'pivots.

2. In a circuit controlling device, the combination of a contact, means for mounting said contact to cause two different points thereon to move in circular paths which have diiferent centers and a cooperating contact pivoted to swing about a point ec-.

centric to one of said centers and thereby move into and out of engagement with 'said first named contact.

3. A circuit controlling device comprising, a contact, a link pivoted to said contact at one point, means cooperating with said contact at another point to constrain said latter point to follow a path which differs from the are described by said first point, both of said points moving in circular paths which have difierent centers, and a cooperating contact pivoted to swing about a point.

eccentric to one of said centers and thereby move into and out of engagement first named contact.

4. A circuit controlling device comprising, a support, a contact mounted on said support, and two links of unequal length with said each pivoted at oneend to diiferent points on said contact and each pivotally mounted at the other end to different points on said support,'s aid links mounted to move said contact toward and away from said support.

5. In a circuit controlling device, the com: bination of a support, two links of unequal length pivoted to said support at different points, a contact pivotally connected near one end to the longer of said links, and a pivotal .lost motion connection between said contact and the shorter of said links at a point near the other end of said contact.

6. In a circuit controlling device, the com-.

bination of a support, two links of unequal length pivoted to said support at diflerent points, a contact pivotally connected at the .outer end of one of said links, and a lost motion connection between the other said link and. said contact for permitting said' contact to move ,to a limited extent toward and away from said support. 7. In a circuit controlling device, the combination with a support, of two links piv: oted to said' support, a contact pivoted to the outer end of 'one of said links and having'a lug pr ojecting toward said support, resilient means connected to said support and to said lug to move said contact away from said' support, and a lost motion connection between said contact and permitting said contact to move toward and away from said support.

8. A circuit controlling devicecompristhe other link -for' ing a support, links of unequal length pivoted cured to the outer ends oi the longer links, said contact having at one end a lug whlch projects toward said support and at the to said support, a-contact pivotally seother end lugs with slots therein, a spring one end of which is secured to said lug and the other end to said support, a pin pivotally connected to the outer ends of the shorter links and extending into the slots in the lugs on said contact to form a lost motion connection therewith, and a flexible conducting connection between said contact and one lead of the circuit to be controlled.

9. Ina circuit controlling device, the combination with a base, of a contact having, each end pivotally linked toisaid base to be movable relatively thereto, and a spring mounted between said contact and said base and connected to move said contact re1a-- 1 tively to said base.

' and to different points on said contact, and

a spring mounted between said contact and said base with one end connected to said base and the other end connected to said contact.

to cause said contact to. move about the piva ,ots of saidolinks as centers.-

In Witness whereof, I have hereunto set my hand this 28th day of October. 1910.

' EDWARD M. HEWLETT. Witnesses: I HELEN Onronn, CHARLES McCmm. 

